Effect of aluminophosphate on catalyst systems comprising metal alkyl cocatalysts

ABSTRACT

Novel catalyst systems which comprise one or more diimine nickel (II) or palladium (II) complexes, one or more cocatalysts, and aluminophosphate are disclosed. Olefin polymerization processes using those catalyst systems are also disclosed. The inclusion of aluminophosphate can improve the activity or productivity of such catalyst systems, making such catalyst systems active or more active in olefin polymerization under conditions in which they had previously been inactive or insufficiently active.

This invention relates to the use of aluminophosphate in catalystsystems comprising nickel and palladium catalysts and metal alkylcocatalysts. This invention also relates to olefin polymerizationprocesses using such catalyst systems to polymerize mono-1-olefins andoptionally one or more co-monomers. The present invention also relatesto polymers made by such processes.

BACKGROUND

It is well known that mono-1-olefins, such as ethylene and propylene,can be polymerized with catalyst systems employing transition metalssuch as titanium, vanadium, chromium, nickel and/or other metals, eitherunsupported or on a support such as alumina, silica, titania, and otherrefractory metals. Supported polymerization catalyst systems frequentlyare used with a cocatalyst, such as alkyl boron compounds and/or alkylaluminum compounds and/or alkyl aluminoxy compounds. Organometalliccatalyst systems, i.e., Ziegler-Natta-type catalyst systems, usually areunsupported and frequently are used with a cocatalyst, such asmethylaluminoxane. Other components may be used in addition to thecatalyst and cocatalyst.

It is also well known that, while no polymer production process is easy,slurry, or loop, polymerization processes are more commerciallydesirable than other polymerization processes, due to ease of operation.Furthermore, the type of polymerization process used can have an effecton the resultant polymer. For example, higher reactor temperatures canresult in low catalyst activity and productivity, as well as a lowermolecular weight polymer product. Higher reactor pressures also candecrease the amount of desirable branching in the resultant polymer.

Most polymer products made using slurry processes, especially polymerproducts made using supported chromium catalyst systems, have a broadermolecular weight distribution and, therefore, the polymer product ismuch easier to process into a final product. Polymers made by otherprocesses, such as, for example, higher temperature and/or higherpressure solution processes, can produce polymers having a narrowmolecular weight distribution; these polymers can be much more difficultto process into an article of manufacture.

Unfortunately, many homogeneous organometallic catalyst systems have lowactivity, high consumption of very costly cocatalysts likemethylaluminoxane (MAO), and can produce low molecular weight polymerswith a narrow molecular weight distribution. Furthermore, even thoughMAO can be helpful or even necessary to produce a polymer with desiredcharacteristics, an excess of MAO can result in decreased catalystsystem activity. Additionally, these types of homogeneous catalystsystems preferably are used only in solution or gas phase polymerizationprocesses.

U.S. Pat. No. 5,648,439 discloses aluminophosphate as the presently mostpreferred catalyst support for the chromium catalyst systems disclosedtherein. The patent does not disclose that aluminophosphate can beemployed in catalyst systems comprising other catalytic metals.

Polymerization processes for olefins using catalyst systems containing anickel or palladium alpha-diimine complex, a metal containinghydrocarbylation compound, and a selected Lewis acid are disclosed inU.S. Pat. No. 5,852,145, the disclosure of which is incorporated hereinby reference. In the '145 patent, the metal containing hydrocarbylationcompound is defined as a compound that can transfer a hydrocarbyl groupto a nickel or palladium compound. The patent states that usefulalkylating agents (which are a form of the metal containinghydrocarbylation compound) have the formulas MX₂R_(n) ⁶ or[Al(O)R¹¹]_(q), which includes alkylaluminum and alkylzinc compoundswhich may or may not have halogen groups as well as alkyl aluminoxanes.In that patent, the selected Lewis acids are referred to as compound(II), and the group consisting of B(C₆F₅)₃, AlCl₃, AlBr₃, Al(OTf)₃ and(R¹³R¹⁴R¹⁵C)Y is particularly disclosed and claimed. The patent statesthat when a hydrocarbylation compound is other than an alkylaluminumcompound containing one or more halogen atoms bound to an aluminum atomor an alkyl aluminoxane, compound (II) must be present. Thus, when thehydrocarbylation compound is R₃Al, compound (II) must be present.

U.S. Pat. No. 5,852,145 does not disclose or suggest aluminophosphate asa suitable compound (II) or a catalyst system that includesaluminophosphate. The patent states that compound (II) may optionally bepresent when the hydrocarbylation compound is R₂AlBr, RAlC₂, or “RAlO”.The patent does not indicate whether including compound (II) with thosehydrocarbylation compounds will improve or alter the activity orproductivity of the catalyst system.

SUMMARY OF THE INVENTION

It is an object of this invention to provide novel catalyst systemsuseful for polymerization.

It is another object of this invention to provide catalyst systems whichare relatively simple to make, have increased activity and increasedproductivity.

It is a further object of this invention to provide catalyst systemswhich employ less costly cocatalysts.

It is an object of this invention to provide a catalyst systemcomprising at least diimine one nickel (II) or palladium (II) complex,at least one cocatalyst and aluminophosphate. Processes for making andusing such catalyst systems are also provided.

It is also an object of this invention to provide an olefinpolymerization process comprising contacting in a reaction zone underpolymerization conditions an olefin monomer and a catalyst systemcomprising at least one diimine nickel (II) or palladium (II) complex,at least one cocatalyst and aluminophosphate.

It is further an object of this invention to provide an active olefinpolymerization catalyst system comprising at least one diimine nickel(II) or palladium (II) complex, at least one cocatalyst, and an amountof aluminophosphate, where the catalyst system would not be active inthe absence of aluminophosphate.

It is also an object of this invention to provide a method of making acatalyst system active or more active in the polymerization of olefinsby adding an effective amount of aluminophosphate.

It is a further object of this invention to provide a process for makingpolyolefins employing diimine nickel or palladium catalyst systems thatheretofore have been considered inactive or insufficiently active inolefins polymerization.

In accordance with this invention, catalyst systems comprising one ormore nickel or palladium catalysts, at least one cocatalyst and aneffective amount of aluminophosphate are provided. The nickel catalystscan be diimine nickel complexes can further comprise additional ligandsselected from the group consisting of α-deprotonated-β-diketones,α-deprotonated-β-ketoesters, halogens and mixtures thereof. In presentlypreferred embodiments, the catalyst systems comprise diimine nickelcomplexes having a formula selected from the group consisting ofNi(NCR′C₆R₂H₃)₂(Y₂C₃R″₂X)₂ and Ni(NCR′C₆R₂H₃)₂(Y₂C₃R″₂X)Z, andNi(NCR′C₆R₂H₃)₂(Y₂C₃R″₂X)₂, and the cocatalyst may be an alkyl aluminumcompound or an alkyl zinc compound. Processes to make these catalystsystems also are provided.

In accordance with another embodiment of this invention, slurrypolymerization processes comprising contacting ethylene, and optionallyone or more higher alpha-olefins, in a reaction zone with heterogeneouscatalyst systems comprising one or more nickel or palladium catalysts,at least one cocatalyst and aluminophosphate are provided. The catalystsystems preferably comprise diimine nickel complexes that may furthercomprise additional ligands selected from the group consisting ofα-deprotonated-β-diketones, α-deprotonated-β-ketoesters, halogens andmixtures thereof.

In accordance with this invention, heterogeneous catalyst systemsconsisting essentially of at least one diimine nickel complex, at leastone cocatalyst, and aluminophosphate are provided. The diimine nickelcomplexes may further comprise additional ligands selected from thegroup consisting of α-deprotonated-β-diketones,α-deprotonated-β-ketoesters, halogens and mixtures thereof. Thecocatalyst can be an alkylaluminum compound or an alkylzinc compound.Processes for making and using these catalyst systems also are provided.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Catalyst Systems

Catalyst systems of the present invention can be characterized ascomprising one or more nickel or palladium catalysts, at least onecocatalyst, and an effective amount of aluminophosphate, wherein theamount of aluminophosphate is sufficient to make the catalyst systemsactive for olefin polymerization, or to improve the activity of thecatalyst systems for olefins polymerization, or to alter the nature ofthe polymer made in an olefin polymerization process using thosecatalyst systems. The nickel and palladium catalysts are preferablydiimine complexes that typically comprise additional ligands selectedfrom the group consisting of α-deprotonated-β-diketones,α-deprotonated-β-ketoesters, halogens and mixtures thereof. Mostpreferably, the catalyst systems comprise at least one diimine nickelcomplex having a formula selected from the group consisting ofNi(NCR′C₆R₂H₃)₂(Y₂C₃R″₂X)₂ and Ni(NCR′C₆R₂H₃)₂(Y₂C₃R″₂X)Z andNi(NCR¹C₆R₂H₃)₂Z₂. Alternatively, the nickel complexes can be selectedfrom the group having one of the formulas shown below in Compounds I andII,

wherein each R is independently selected from the group consisting ofhydrogen and alkyl or aromatic groups having from about 1 to about 10,preferably from about 1 to about 8, carbon atoms per alkyl group,wherein said alkyl groups may be branched or linear and the Rsubstituents on the aromatic ring may be the same or different, and theR substituents can be in any position on the aromatic ring; and

wherein each R′ is independently selected from the group consisting ofhydrogen and linear, branched, cyclic, bridging, aromatic, and/oraliphatic hydrocarbons, having from about 1 to about 70, preferably fromabout 1 to about 20, carbon atoms per radical group and wherein the R′substituents on the aromatic ring can be the same or different.

The R substituents on the aromatic rings of the diimine nickel complexin Compounds I and II can be the same or different, and they areindependently selected from the group consisting of branched or linearalkyl (aliphatic) or aromatic groups having from about 1 to about 10,preferably from about 1 to about 8, carbon atoms per alkyl group.Although hydrogen can be used, hydrogen can inhibit synthesis of theligand. R substituents having more than about 8 carbon atoms per groupcan result in a catalyst system with lower activity and/or productivity.Similarly, having more than two R substituents on the aromatic ring canresult in a catalyst system with lower activity and/or productivity.While not wishing to be bound by theory, it is believed that larger ormore substituent groups can cause steric hindrance in the catalystsystem, which can thereby decrease catalyst system activity and/orproductivity and/or ease of synthesis of the catalyst. Nonetheless,under some circumstances, having larger or more R substituents mayprovide advantages that compensate for lower activity and/orproductivity. Thus, having larger or more substituents is not excluded.Exemplary alkyl substituents are selected from the group consisting ofmethyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, benzyl,phenyl groups, and mixtures of two or more thereof. Preferably, the Rsubstituent is an electron-donating species, selected from the groupconsisting of linear or branched aliphatic groups having from about 1 toabout 5 carbon atoms per group. Most preferably, the R substituents areboth the same and are selected from the substituents consisting ofmethyl and isopropyl, due to commercial availability and ease ofsynthesis of the ligand.

The R substituent can be in any position on the aromatic ring, i.e.,from the 2 to 6 position. Preferably, the R substituent is either in the2 or 6 position, due to ease of synthesis. Where there are two Rsubstituents, they may be the same or different, and it is preferredthat they are the same and in the 2 and 6 positions, for best catalyticactivity and productivity.

The R′ substituents can be the same or different and are independentlyselected from the group consisting of hydrogen and branched, linear,cyclic, aromatic or aliphatic radicals having from about 1 to about 70carbon atoms per radical. Further, the R′ substituents can be linked, orjoined, across the carbon-carbon bridge between the two nitrogen atoms.While not wishing to be bound by theory, it is believed that radicalshaving more than 70 carbon atoms can add to the steric hindrance of thecatalyst systems and hinder catalyst synthesis and/or activity andproductivity. Preferably, the R′ substituent is selected from the groupconsisting of hydrogen and branched, linear, cyclic, aromatic oraliphatic radicals having from about 1 to about 20 carbon atoms perradical, due to commercial availability and ease of synthesis of theligand. Most preferably, the R′ substituents are the same or form a linkin addition to the carbon-carbon bridge between the nitrogen atoms.Also, the R′ substituent is selected from the group consisting ofhydrogen and branched, linear, cyclic, aromatic or aliphatic radicalshaving from about 1 to about 12 carbon atoms per radical, for thereasons given above. Exemplary R′ substituents include, but are notlimited to, hydrogen, methyl, ethyl, propyl, phenyl, or when the R′substituents are linked, they preferably form acenaphthyl orcyclobutadienyl. Preferably, the R′ substituents are identical and areselected from the group consisting of hydrogen, methyl and acenaphthylfor best resultant catalyst system activity and productivity.

In the formulas and compounds above, the R″CYCXCYR″ substituents orligands (also written as Y₂C₃R″₂X) on the diimine complex can be thesame or different and are selected from the group consisting ofα-deprotonated-β-diketones, α-deprotonated-β-ketoesters, halogens andmixtures thereof The R″ substituents can be the same or different. Theα-deprotonated-β-diketones and α-deprotonated-β-ketoesters can bederived from β-diketone and β-ketoester ligand precursors. Exemplaryligand precursors include, but are not limited to, compounds selectedfrom the group consisting of 2,4-pentanedione,1,1,1,5,5,5-hexafluoro-2,4-pentanedione, allylacetonacetate,benzoylacetonate, benzoyl-1,1,1-trifluoroacetone,1,1,1-trifluoro-2,4-pentanedione, 1-chloro-1,1-difluoroacetylacetonemethyl-4,4,4-trifluoroacetoacetate,1,1,1-trifluoro-5,5-dimethyl-2,4-pentanedione, ethylα-methyl-4,4,4-trifluoroacetoacetate,4,4,4-trifluoro-1-(2-furyl)-1,3-butanedione, and2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedione. Preferably,ligand precursors are selected from the group consisting of2,4-pentanedione, 1,1,1,5,5,5-hexafluoro-2,4-pentanedione,1,1,1-trifluoro-2,4-pentanedione, 1-chloro-1,1-difluoroacetylacetone,methyltrifluoroacetoacetate,1,1,1-trifluoro-5,5-dimethyl-2,4-pentanedione, and ethylα-methyl-4,4,4-trifluoroacetoacetate. Most preferably, ligands include,but are not limited to 2,4-pentanedione,1,1,1,5,5,5-hexafluoro-2,4-pentanedione,1,1,1-trifluoro-2,4-pentanedione, 1-chloro-1,1-difluoroacetylacetone,and 1,1,1-trifluoro-5,5-dimethyl-2,4-pentanedione for best catalystsystem activity as well as best polymer product properties.

Group Z, which is a halogen, of the diimine complex is selected from thegroup consisting of fluorine, chlorine, bromine and/or iodine.Preferably, the halogen is selected from the group consisting ofchlorine and/or bromine for high catalyst activity and productivity.Most preferably, the halogen is chlorine for best catalyst systemactivity and productivity.

The catalyst systems can comprise more than one diimine complex.Contemplated for use in this invention, a catalyst system comprising twoor more diimine nickel or palladium complexes may be employed in apolymerization process to produce a polymer having a multimodalmolecular weight distribution.

The diimine metal complexes disclosed herein can be prepared accordingto any method known in the art. For example, approximate molarequivalents of a diimine ligand and a nickel or palladium compound canbe contacted in the presence of any compound that can dissolve both thediimine ligand and metal compound, either partially or completely. Thecontacting conditions can be any conditions suitable to effect theformation of a diimine nickel or palladium complex. Preferably, for bestproduct results, the diimine ligand/metal complex mixture is contactedat room temperature under a dry atmosphere for any amount of timesufficient to form the diimine metal complex. Completion of theformation of the diimine metal complex can be evidenced by a colorchange. Generally, contacting times of at least about 8 hours, andpreferably at least about 12 hours are sufficient. Usually, as a resultof the preparation procedure, the resultant diimine metal complex willcomprise from about 3 to about 20, preferably from about 5 to about 15,weight percent nickel, based on the total mass of the diimine metalcomplex. The presence of oxygen is not thought to be detrimental to thisaspect of the preparation procedure.

In general, diimine ligands are contacted with a nickel β-diketonate ornickel β-diketonate halide to form diimine nickel complexes. Typicalsyntheses of nickel complexes related to those described in thisinvention can be found in Dieck, H., Svboda, M., and Greiser, T., Z.Naturforsch B: Anorg. Chem. Organ. Chem., Vol. 36b, pp. 823-832 (1981),herein incorporated by reference. Usually, for ease of catalyst systempreparation, the diimine ligand is prepared first. The catalystpreparation procedure can vary, depending on the substituents on thediimine ligand. For example, to prepare a specific diimine ligand,wherein R′ is hydrogen, a three component mixture is prepared. Atwo-fold molar excess of aniline, containing the desired R substituents(R_(n)C₆H_((7−n))N, wherein n=1 or 2), is contacted with a dialdehyde,such as, for example, glyoxal (CHOCHO), in the presence of a compoundcapable of being a solvent for both organic and aqueous compounds.Exemplary solvents for both organic and aqueous compounds include, butare not limited to, methanol, ethanol and/or tetrahydrofuran (THF). Themixture can be contacted, preferably refluxed, under any atmosphere toform the desired ligand. Preferably, the mixture is refluxed for atleast 10, preferably 20 minutes, cooled and the desired ligand can berecovered. Generally, after refluxing and cooling, the ligand can berecovered in a crystalline form.

To prepare another specific diimine ligand wherein the R′ group isanything other than hydrogen, a similar procedure can be used. Forexample, at least a two-fold molar excess of aniline or a substitutedaniline can be combined with a compound capable of dissolving bothorganic and aqueous compounds and a very minor amount of formic acid.Then, about a one molar equivalent of an alpha-diketone (R′COCOR′) canbe added to the mixture. The mixture can be stirred, under atmosphericconditions of temperature and pressure until the reaction is completeand the desired ligand is formed. Preferably, water is absent from thereaction mixture. Generally, the reaction can be completed in about 18,preferably 24 hours. A crystalline ligand product can be recoveredaccording to any method known in the art.

The nickel bis(β-diketonate), nickel bis(β-ketoester), nickelβ-diketonate halide and nickel β-ketoester halide can be prepared by anymethod known in the art. Typical syntheses of such nickel complexes canbe found in Bullen, G. J., Mason, R., and Pauling, P., InorganicChemistry, Vol. 4, pp. 456-462 (1965), herein incorporated by reference.Alternatively, and especially in the case of nickel β-diketonate halidesand nickel β-ketoester halides, the salt of the β-diketone orβ-ketoester can be prepared then reacted with the correct quantity ofnickel halide. A mixture of an appropriate Brönsted base, such as butnot limited to sodium or potassium hydride or sodium or potassiummethoxide, is mixed with a solvent capable of dissolving or becomingmiscible with the β-diketone or β-ketoester. Exemplary solvents includetoluene, benzene, methanol, or ethanol. One molar equivalent of theβ-diketone or β-ketoester is added slowly to this mixture. Reaction isknown to occur as evidenced by the evolution of heat and a change in thephysical appearance of the mixture.

Once all reactants have contacted, reaction times from about 4 to about12 hours are sufficient to ensure complete reaction. If the product saltof the β-diketone or β-ketoester is not soluble in the solvent chosen,the solvent is removed by filtration or vacuum and the salt dissolved ina solvent in which it is soluble. Exemplary solvents include, but arenot limited to, methanol and ethanol. This solution then is added to aone half molar equivalent of nickel halide that has been suspended ordissolved in the same solvent or a solvent with which the first solventis miscible. The preceding reactant ratio results in the formation ofthe nickel bis(β-diketonate) or nickel bis(β-ketoester). If the nickelβ-diketonate halide or nickel β-ketoester halide are desired, thesolution is added to one molar equivalent of nickel halide as described.Reaction is known to occur as evidenced by the formation of a solublegreen species. Reaction times of from about 4 to about 12 hours aresufficient to ensure complete reaction. Byproduct sodium or potassiumhalide salt can be removed from the reaction product by filtrationand/or centrifugation. The solvent can be removed by vacuum to yield thenickel complex used in the nickel diimine complex synthesis.

After formation of a diimine nickel complex, the diimine nickel complexcan be recovered by any method known in the art, such as, for exampleevaporation and/or vacuum filtration of the solvent. If desired, thediimine nickel complex can be further purified by washing. One exemplarywash compound can be heptane. The diimine nickel complex catalyst systemcan be recovered and used as part of a system.

The catalyst systems of the present invention generally include one ormore cocatalysts, although in some circumstances, the cocatalyst can beomitted or combined with another component of the catalyst system.Exemplary cocatalysts include, but are not limited to, metal alkyl,cocatalysts such as alkyl boron compounds and/or alkyl aluminumcompounds and/or alkyl aluminoxy compounds. Other examples ofcocatalysts include alkyl zinc compounds. It is contemplated that insome embodiments, the cocatalyst can be aluminum compounds of theformula AlR² _(n)X_(3−n) or zinc compounds of the formula ZnR²_(m)X_(2−m), where X is a hydride or halide, R² is a hydrocarbyl radicalhaving 1 to 12 carbon atoms, and the R² substituents can be the same ordifferent, and n is an integer of 1 to 3, and m is an integer of 1 to 2.Trimethyl aluminum, diethyl zinc, diethyl aluminum chloride, and ethylaluminum dichloride are non-limiting examples of suitable cocatalysts.

A cocatalyst, when used, can be used in any amount to improve catalystsystem activity and productivity. Further, the amount of cocatalystadded to the reactor can vary. Generally, a molar excess of MAO ispresent, relative to the diimine nickel complex. Preferably, the metalin the cocatalyst to metal in the catalyst system (Ni or Pd) (cocatalystmetal:catalyst metal) molar ratio is less than about 1500:1, morepreferably within a range of about 50:1 to about 600:1. Most preferably,the molar ratio of metal in the cocatalyst to metal in the catalystsystem (Ni or Pd) is within a ratio of 100:1 to 400:1 for best catalystsystem activity and productivity.

The cocatalyst either can be premixed with the diimine nickelcomplex(es) or added as a separate stream to the polymerization zone.

Catalyst systems of the present invention further comprisealuminophosphate, also referred to as AlPO₄. Aluminophosphate isdisclosed in U.S. Pat. No. 4,364,855, the entirety of which is hereinincorporated by reference. Generally, the P/Al molar ratio of thealuminophosphate is within a range of about 0.2 to about 1.0 andpreferably within a range of about 0.4 to about 0.9. Thealuminophosphate can be used as a support for the catalyst system or itcan be included in addition to another catalyst support such as aninorganic oxide. Exemplary inorganic oxides include, but are not limitedto, silica, silica-alumina, alumina, fluorided alumina, silated alumina,fluorided/silated alumina, thoria, aluminum phosphate, phosphatedsilica, phosphated alumina, silica-titania, coprecipitatedsilica/titania, and mixtures thereof.

The aluminophosphate can be activated prior to use or inclusion in thecatalyst system. The aluminophosphate can be activated at a temperaturewithin a range of about 200° C. to about 1000° C., preferably within therange of about 500° C. to about 800° C., most preferably at about 600°C. to about 700° C. for 3 to 4 hours.

The inclusion of aluminophosphate in certain catalyst systems comprisinga nickel or palladium catalyst and a cocatalyst can improve theproductivity of those catalyst systems. In some circumstances, catalystsystems that are not active or are insufficiently active in thepolymerization of olefins can be made active or more active by theinclusion of aluminophosphate in the catalyst system.

The amount of aluminophosphate included in the catalyst system dependsin part on the amounts and types of nickel complexes and cocatalystsemployed. The determination of an effective amount of aluminophosphatefor the desired purpose will not present difficulty in view of thepresent disclosure. It is contemplated that the preferred molar ratio ofaluminum in AlPO₄ included in the catalyst system to metal in thecatalyst can be within a range of from about 10:1 to about 100,000:1,preferably from about 50:1 to about 10,000:1. Most preferably the molarratio of aluminum in AlPO₄ included in the catalyst system to metal inthe catalyst is within a range of 100:1 to 5000:1.

It has been found by the present inventors that catalyst systems havinga diimine nickel complex and a cocatalyst that is a trialkyl aluminum ora dialkyl zinc are not active as olefin polymerization catalyst systems.However, by including an effective amount of aluminophosphate in thosecatalyst systems, it has been found that those catalyst systems becomeactive as olefins polymerization catalyst systems. It has been foundthat other catalyst systems having a diimine nickel complex and acocatalyst that is an alkyl aluminum halide or an alkyl zinc halide areactive as olefin polymerization catalyst systems; however, it has beenfound that the inclusion of aluminophosphate can increase theproductivity of those catalyst systems or lower the density ofpolyethylene made using one such catalyst system.

Reactants, Polymerization and Polymer Products

Polymers produced according to the process of this invention can behomopolymers of mono-1-olefins or copolymers of at least two differentmono-1-olefins. Exemplary mono-1-olefins useful in the practice of thisinvention include but are not limited to mono-1-olefins having fromabout 2 to about 10 carbon atoms per molecule. Preferred mono-1-olefinsinclude, but are not limited to ethylene, propylene, 1-butene,1-pentene, 1-hexene, 1-heptene, 3-methyl-1-butene, 4-methyl-1-pentene,1-octene, 1-nonene and 1-decene. If the reaction product is a copolymer,one mono-1-olefin monomer can be polymerized with a mono-1-olefincomonomer which is a different alpha olefin, usually having from about 3to about 10, preferably from 3 to 8 carbon. atoms per molecule.Exemplary comonomers include, but are not limited to, propylene,1-butene, butadiene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene,and mixtures thereof. Preferably, if the monomer is ethylene, thecomonomer is 1-hexene and/or 4-methyl-1-pentene, in order to achievemaximum polymer product toughness. Preferably, if the monomer ispropylene, the comonomer is ethylene and/or butadiene in order toachieve maximum polymer product toughness and clarity.

If a comonomer is used, the comonomer can be added to the polymerizationreactor, or reaction zone, in an amount within a range of about 1 toabout 20 weight percent, preferably within 7 to about 18 weight percent,based on the weight of the ethylene monomer. Most preferably, acomonomer is present in the reaction zone within a range of about 10 toabout 16 weight percent, in order to produce a polymer having the mostdesired physical properties.

Polymerization of the monomer and optional comonomer may be carried outunder slurry polymerization conditions, also known as loop/slurry orparticle form polymerization conditions. Under such conditions, thetemperature is kept below the temperature at which polymer swellssignificantly. Slurry polymerization processes are much easier tooperate and maintain than other polymerization processes; a polymerproduct produced by a slurry process can be recovered much more easily.Such polymerization techniques are well-known in the art and aredisclosed, for instance, in Norwood, U.S. Pat. No. 3,248,179, thedisclosure of which is hereby incorporated by reference.

The slurry process generally is carried out in an inert diluent(medium), such as, for example, a paraffin, cycloparaffin, and/oraromatic hydrocarbon. Preferably, the inert diluent is an alkane havingless that about 12 carbon atoms per molecule, for best reactor operationand polymer product. Exemplary diluents include, but are not limited topropane, n-butane, isobutane, n-pentane, 2-methylbutane (isopentane),and mixtures thereof. Isobutane is the most preferred diluent due to lowcost and ease of use.

The temperature of the polymerization reactor, or reaction zone, whenusing isobutane as the reactor diluent, according to this invention, iscritical and must be kept within a range of about 5° C. to about 100° C.(41° F.-212° F.) and preferably within a range of about 10° C. to about70° C. (50° F. -158° F.). Most preferably, the reaction zone temperatureis within a range of 20° C. to 60° F. (68° F.-140° C.) for best catalystactivity and productivity. Reaction temperatures below about 10° C. canbe ineffective for polymerization.

Pressures in the slurry process can vary from about 100 to about 1000psia (0.76-7.6 MPa), preferably from about 200 to about 700 psia. Mostpreferably, the reaction zone is maintained at a pressure within a rangeof 300 to 600 psia for best reactor operating parameters and bestresultant polymer product. The catalyst system is kept in suspension andis contacted with the monomer and comonomer(s) at sufficient pressure tomaintain the medium and at least a portion of the monomer andcomonomer(s) in the liquid phase. The medium and temperature are thusselected such that the polymer or copolymer is produced as solidparticles and is recovered in that form. Catalyst system concentrationsin the reactor can be such that the catalyst system content ranges from0.001 to about 1 weight percent based on the weight of the reactorcontents.

The nickel or palladium catalyst, cocatalyst and aluminophosphate can beadded to the reactor in any order to effect polymerization. For example,a diimine nickel complex can be added, then some reactor diluent, suchas isobutane, followed by aluminophosphate, then by cocatalyst, thenmore diluent and finally, monomer and optional comonomer. Alternatively,a diimine nickel complex and aluminophosphate can be combined prior toaddition to the reactor. However, as stated earlier, this addition ordercan be varied, depending on equipment availability and/or desiredpolymer product properties. Preferably, the catalyst system andcocatalyst are not precontacted prior to addition to the polymerizationreactor due to a possible decrease in catalyst system activity.

The amounts of nickel or palladium catalyst system, cocatalyst, andaluminophosphate added to the reactor can vary. Generally, a molarexcess of cocatalyst can be present, relative to the catalyst system.Preferably, the aluminum to nickel (Al:Ni) molar ratio or the zinc tonickel molar ratio (Zn:Ni) is less than about 1500:1, more preferablywithin a range of about 50:1 to about 600:1. Most preferably, the molarratio of aluminum to nickel, or zinc to nickel, is within a ratio of100:1 to 400:1 for best catalyst system activity and productivity.Similar molar ratios of Al:Pd and Zn:Pd can be used.

Two preferred polymerization methods for the slurry process are thoseemploying a loop reactor of the type disclosed in Norwood and thoseutilizing a plurality of stirred reactors either in series, parallel orcombinations thereof wherein the reaction conditions can be the same ordifferent in the different reactors. For instance, in a series ofreactors, a chromium catalyst system which has not been subjected to thereduction step can be utilized either before or after the reactorutilizing the catalyst system of this invention.

Polymers produced by using diimine nickel complexes generally havereduced cocatalyst consumption and tend to use cocatalysts, such as MAO,efficiently and productively.

Polymers produced by using single diimine nickel complexes generallyhave a relatively narrow heterogeneity index (HI), which is a ratio ofthe weight average molecular weight (M_(w)) and the number averagemolecular weight (M_(n)) also expressed as M_(w)/M_(n). However,polymers produced by using a catalyst system comprising two differentdiimine nickel complexes usually can have a relatively widerheterogeneity index.

Polymers produced by using single diimine nickel complexes are veryunique because of a significant amount of short chain branching whichcan be produced even in the absence of a comonomer added to the reactor.This short chain branching is evidence that some sort of comonomers areproduced in-situ in the reactor and are incorporated into the polymerand/or that the catalyst can form short chain branches by rearrangementof the main polymer chain through successive hydride elimination, olefinrotation, and hydride re-addition reactions. This series of steps may ormay not involve discrete intermediates and may rather be a concerted orcontinuous series of reactions with no distinct intermediates formed.Such rearrangements can be termed “chain walking”. Chain walking can bedescribed by the active metal catalyst, i.e. nickel, Awalking@ adistance along the polymer backbone during polymerization and hence, theshort chain branch length can be dictated by the rate of ethyleneinsertion relative to the combined rates of hydride elimination, olefinsrotation, and hydride re-addition. Usually, polymers produced inaccordance with this invention, wherein no comonomer is added to thepolymerization reactor, comprise up to about 3000, and generally fromabout 20 to about 3000 short chain branches per 10,000, or from about 2to about 300 short chain branches per 1000, backbone carbon atoms of thepolymer. Furthermore, the short chain branches produced comprise bothodd and even carbon branches, i.e., branches comprising an odd number ofcarbon atoms per short chain branch, as well as branches comprising aneven number of carbon atoms per short chain branch.

If desired, optional addition of one or more comonomers can be added tothe polymerization reactor. The affirmatively added comonomers canfurther increase the amount of short chain branching in the resultantpolymer, or copolymer. Polymers produced with the addition of acomonomer can have a greater number of short chain branches in additionto those generated as described above. If a comonomer is affirmativelyadded to the polymerization reactor, these polymers usually can compriseup to about 3500, and generally from about 20 to about 3500, short chainbranches per 10,000 backbone carbon atoms of polymer.

A further understanding of the invention and its advantages is providedby the following examples.

EXAMPLES

The following Examples illustrate various aspects of the invention. Dataabout polymerization conditions and the nature of the resultant polymerare provided below. All chemical handling, including reactions,preparation and storage, was performed under a dry, inert atmosphere(usually nitrogen). Unless otherwise indicated, bench scalepolymerizations were completed in a 2.6 liter autoclave reactor at thedesired temperature using an isobutane (1.2 liter) slurry. The reactorwas heated to 120° C. and purged with nitrogen for about 20 minutes. Thereactor then was cooled to the desired polymerization temperature andpressurized with isobutane to about 400 psig. A known quantity (mass) ofdiimine nickel complex catalyst was charged to the reactor against acountercurrent of isobutane and the agitator was set at 490 rpm. Ifhydrogen was charged to the reactor, hydrogen addition was followed byisobutane. The indicated quantity of cocatalyst was charged directly tothe reactor via syringe. After the full volume of isobutane was added,ethylene was added to bring the total reactor pressure to 550 psig.Ethylene was fed on demand and the polymerization reaction terminatedwhen ethylene flow into the reactor ceased.

The diimine nickel complex used in each of the Runs wasN,N′-bis(2,6-diisopropylphenyl)-2,3-butanediimine nickel(II)bis(1,1,1,5,5,5-hexafluoroacetylacetonate), which is abbreviated as

[(iPr₂Ph)₂DABMe₂]Ni(hfacac)₂, as depicted in the Figure below.

The aluminophosphate (AlPO₄) activator is described as having aphosphorous to aluminum molar ratio of 0.8. The aluminophosphate iscalcined at 600-700° C. for 3.5 hr in air then cooled prior to additionto the polymerization reactor.

However, it is contemplated that other diimine nickel complex may beused, as well as other nickel and palladium catalysts. Illustrativeexamples of diimine nickel complexes (preceded by their abbreviations)that may be used in the present invention include, but are not limitedto,

[(iPr₂Ph)₂DABMe₂]Ni(acac)₂-N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediiminenickel(II) bis(acetylacetonate);

[(iPr₂Ph)₂DABMe₂]Ni(hfacac)Cl-N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediimine nickel(II) (1,1,15,5,5-hexafluoroacetylacetonate)chloride;

[(iPr2Ph)₂DABMe₂]Ni(allOacac)₂-N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediiminebis(allylacetylacetonato) nickel(II);

[(iPr₂Ph)₂DABMe₂]Ni(Phacac)₂-N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediiminenickel(II) bis(benzoylacetonate);

[(iPr₂Ph)₂DABMe₂]Ni(PhCF₃acac)₂-N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediiminenickel(II) bis(benzoyl-1,1,1-trifluoroacetonate);

[(iPr₂Ph)₂DABMe₂]Ni(CF₃acac)₂-N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediiminenickel(II) bis(1,1,1-trifluoroacetylacetonate);

[(iPr₂Ph)₂DABMe₂]Ni(CClF₂acac)₂-N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediiminenickel(II) bis(1-chloro-1,1-difluoroacetylacetonate);

[(iPr₂Ph)₂DABMe₂]Ni(CF₃MeOacac)₂-N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediiminebis(methyltrifluoroacetoacetonato) nickel(II);

[(iPr₂Ph)₂DABMe₂]Ni(CF₃tBuacac)₂-N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediiminenickel(II) bis(1,1,1-trifluoro-5,5-dimethylacetylacetonate);

[(iPr₂Ph)₂DABMe₂]Ni(CF₃OEt-α-Meacac)₂-N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediiminebis(ethyl α-methyl-4,4,4-trifluoroacetoacetato) nickel(II);

[(iPr₂Ph)₂DABMe₂]Ni(CF₃furacac)₂-N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediiminenickel(II) bis(4,4,4-trifluoro-1-(2-furyl)acetylacetonate);

[(iPr2Ph)₂DABMe₂]Ni(CF₃CF₂CF₂tBuacac)₂-N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediiminenickel(II) bis(2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedionate)

[(iPr₂Ph)₂DABAn]Ni(hfacac)₂-N,N′-bis(2,6-diisopropylphenyl)acenaphthylnickel(II) bis(hexafluoroacetylacetonate);

[(Me₂Ph)₂DABH₂]Ni(acac)₂-N,N′-bis(2,6-dimethylphenyl)-1,2-ethylenediiminenickel(II) bis(acetylacetonate);

[(iPr₂Ph)₂DABH₂]Ni(hfacac)₂-N,N′-bis(2,6-diisopropylphenyl)-1,2-ethylenediiminenickel(II) bis(hexafluoroacetylacetonate);

[(Me₂Ph)₂DABH₂]Ni(hfacac)₂-N,N′-bis(2,6-dimethylphenyl)-1,2-ethylenediiminenickel(II) bis(hexafluoroacetylacetonate);

[(Me₂Ph)₂DABMe₂]Ni(acac)₂-N,N′-bis(2,6-dimethylphenyl)-2,3-butanediiminenickel(II) bis(acetylacetonate);

and mixtures of two or more thereof.

In general, catalysts systems used for polymerization in the Exampleswere prepared as described herein.

The Table columns convey the following information. Mass Ni complex(grams) is the mass of [(iPr₂Ph)₂DABMe₂]Ni(hfacac)₂ charged to thepolymerization reactor for each Run. Mass Support (grams) is the mass ofaluminophosphate charged to the reactor for each Run. Polymer densitywas determined in grams per cubic centimeter (g/cc) on a compressionmolded sample, cooled at about 15° C. per hour, and conditioned forabout 40 hours at room temperature in accordance with ASTM D1505 andASTM D1928, procedure C. High load melt index (HLMI, g/10 mins) wasdetermined in accordance with ASTM D1238 at 190° C. with a 21,600 gramweight. Melt index (MI, g/10 mins) was determined in accordance withASTM D1238 at 190° C. with a 2,160 gram weight. Values that were notdetermined are represented as “ND” in the Tables.

Example 1

The following experiments show the effect of added aluminophosphate tothe reaction system with 0.5 mL of 2M trimethylaluminum (TMA) in hexanesas the alkylating agent. All experiments were performed at 60° C. inisobutane. No polymer is formed in the absence of the aluminophosphatewith trimethylaluminum.

TABLE 1 Mass Ni Mass Run com- AlPO₄ Productivity MI HLMI Density No.plex (g) (g) (g PE/g Ni) (g/10 min) (g/10 min) (g/cc) 101 0.0167 0     0102 0.0045 0.47 60300 0 0 0.904 103 0.0087 0.55 38100 0 0 0.901 1040.0430 0.53 60000 0 0 0.898

Runs 101 is comparative example in which no aluminophosphate, Runs102-104 are embodiments which included aluminophosphate in the catalystsystem. The data in Table 1 show that catalyst systems comprising adiimine nickel(II) complex and trimethyl aluminum (TMA) can effectivelypolymerize ethylene when aluminophosphate is included in the catalystsystem, as in Runs 102-104. In contrast, catalyst systems comprising thesame diimine complex and TMA without aluminophosphate were not active ascatalysts for olefin polymerization, as in Run 101. Thus, Example 1shows that the inclusion of aluminophosphate can render an inactivecatalyst system comprising an alkyl aluminum cocatalyst active forolefins polymerization.

Example 2

The following experiments show the effect of varying the quantity ofalkylating agent on the productivity of the catalyst with addedaluminophosphate. The addition of large quantities of alkylating agentappears to decrease catalyst system productivity. Note that Run 201 isthe same as Run 102.

TABLE 2 Produc- Mass Ni Mass Volume tivity MI HLMI Run com- support TMA(g PE/g (g/10 (g/10 Density No. plex (g) (g) (mL) Ni) min) min) (g/cc)201 0.0045 0.47 0.5 60300 0 0 0.904 202 0.0430 0.50 2   51400 0 0 0.898203 0.0400 0.50 5   26600 0 0 0.896

Example 3

The following experiments show the effect of added aluminophosphate tothe reaction system with two different volumes of 15% weight/weightdiethylzinc (DEZ) as the alkylating agent. All experiments wereperformed at 60° C. in isobutane. No polymer is formed in the absence ofthe aluminophosphate with diethylzinc. Thus, catalyst systems comprisingcocatalysts other than aluminum-based cocatalysts can benefit from theinclusion of aluminophosphate in the catalyst system.

TABLE 3 Produc- Mass Ni Mass Volume tivity MI HLMI Run com- AlPO₄ DEZ (gPE/g (g/10 (g/10 Density No. plex (g) (g) (mL) Ni) min) min) (g/cc) 3010.0396 0   1   0 302 0.0430 0.55 1 34500 0 0   0.898 303 0.0428 0   5  0 304 0.0380 0.50 5 27200 0 0.05 0.901

Run 301 and 303 are comparative examples in which no aluminophosphatewas included in the catalyst system, while Runs 302 and 304 wereembodiments which included aluminophosphate in the catalyst system. Thedata in Table 3 show that catalyst systems comprising a diiminenickel(II) complex and diethyl zinc (DEZ) can effectively polymerizeethylene when aluminophosphate is included in the catalyst system, as inRuns 302 and 304. In contrast, catalyst systems comprising the samediimine nickel complex and DEXZ were not active as catalyst systems forolefin polymerization, as in Runs 301 and 303. Thus, Example 3 showsthat the inclusion of aluminophosphate can render an inactive catalystsystem comprising an alkyl zinc cocatalyst active for olefinpolymerization.

Example 4

The following experiments show the effect of added aluminophosphate tothe reaction system with two different volumes of 25.6% weight/weightdiethylaluminum chloride (DEAC) as the alkylating agent. All experimentswere performed at 60° C. in isobutane. The addition of aluminophosphatecauses a slight increase in productivity at low levels ofdiethylaluminum chloride. Improved catalyst system productivity can beachieved by including aluminophosphate in a catalyst system comprising adiimine nickel complex and an alkyl metal monohalide, such as diethylaluminum chloride. At higher levels of diethylaluminum chloride, theaddition of aluminophosphate causes a more substantial increase incatalyst system productivity.

TABLE 4 Produc- Mass Ni Mass Volume tivity MI HLMI Run com- AlPO₄ DEAC(g PE/g (g/10 (g/10 Density No. plex (g) (g) (mL) Ni) min) min) (g/cc)401 0.0385 0   1 11000 0 0.41 <0.880   402 0.0430 0.50 1 12200 0 0.3 0.888 403 0.0406 0   5  5300 0 0.19 0.892 404 0.0440 0.55 5 11000 0 0.350.880

Runs 401 and 403 are comparative examples in which no aluminophosphatewas included in the catalyst system while Runs 402 and 404 areembodiments which included aluminophosphate. The data in Table 4 showthat catalyst systems comprising a diimine nickel(II) complex anddiethyl aluminum chloride are active as olefin polymerization catalysts,but their productivity was improved by the inclusion of aluminophosphatein the catalyst system. Thus, Example 4, again, teaches that theinclusion of aluminophosphate can improve the activity and/orproductivity of a catalyst system comprising an alkyl metal monohalidecocatalyst.

Example 5

The following experiments show the effect of added aluminophosphate tothe reaction system with 25% weight/weight ethylaluminum dichloride(EADC) as the alkylating agent. All experiments were performed at 60° C.in isobutane. This example shows that the catalytic activity of certaincatalyst systems comprising a diimine nickel complex and an alkyl metaldihalide can be altered and improved by including aluminophosphate inthe catalyst system. The addition of aluminophosphate causes a drop inproductivity at high levels of diethylaluminum chloride.

TABLE 5 Produc- Mass Ni Mass Volume tivity MI HLMI Run com- AIPO₄ EADC(g PE/g (g/10 (g/10 Density No. plex (g) (g) (mL) Ni) min) min) (g/cc)501 0.0393 0   5 43200 0   0.02 0.904 502 0.0500 0.49 5 19700 0.01 0.64<0.880  

Runs 501 and 503 are comparative examples in which no aluminophosphatewas included in the catalyst system. The data in Table 5 shows thatcatalyst systems comprising a diimine nickel(II) complex and ethylaluminum dichloride are active as olefin polymerization catalysts, andthe effect of the inclusion of aluminophosphate in the catalyst systemis dependent upon the amount of ethyl aluminum dichloride in thecatalyst system. Runs 503 and 504 indicate that the use of a relativelylarge amount of metal alkyl dichloride relative to the aluminophosphateand/or the diimine nickel complex results in decreased productivity, butalso results in lower density of the polymer produced. Similarly, inRuns 403 and 404 in Example 4, the catalyst system that includedaluminophosphate also produced polymer having a lower density, howeverthat catalyst system also had improved productivity, as compared to thecatalyst system without AlPO₄. When a relatively lower amount of metalalkyl dichloride was employed, as in Runs 501 and 502, the inclusion ofaluminophosphate in the catalyst system increased the productivity inolefin polymerization, from 32000 grams of polyethylene per gram ofnickel complex to 83900 grams of polyethylene per gram of nickelcomplex.

It has been observed that catalyst systems comprising [(iPr₂Ph)₂ DABMe₂]Ni(hfacac)₂ and halogenated cocatalysts, such as DEAC and EADC, as inthe Runs in Examples 4 and 5 tended to produce polyethylene having alower molecular weight, as evidenced by HLMI and having a more highlybranched character, as evidenced by density, than did catalyst systemscomprising the same nickel complex and non-halogenated cocatalysts, asin Examples 1 and 2. This was observed both in the presence and absenceof aluminophosphate in the catalyst system. The effect of cocatalyst onthe branching of polymers produced using nickel catalysts has beendiscussed in the literature, for example, in Pappalardo et al.,Macromol. Rapid Commun. 1997, 18, 1017-1023.

Example 6

The following experiments show the effect of added aluminophosphate tothe reaction system with two different amounts of 25% weight/weightethylaluminum dichloride as the alkylating agent. All experiments wereperformed at 60° C. in isobutane. The addition of large quantities ofethylaluminum dichloride causes a drop in the catalyst's productivity inthe presence of the aluminophosphate. Note that Run 602 is the same asRun 502.

TABLE 6 Produc- Mass Ni Mass Volume tivity MI HLMI Run com- AlPO₄ EADC(g PE/g (g/10 (g/10 Density No. plex (g) (g) (mL) Ni) min) min) (g/cc)601 0.0375 0.56 1 83854 0   0.005 0.887 602 0.0500 0.49 5 19731 0.010.64  <0.880  

Example 7

This example shows that increasing the quantity of ethylaluminumdichloride (25% weight/weight) in the absence of the aluminophosphatedoes not result in the drop in productivity as seen in the presence ofthe aluminophosphate. Note that Run 702 is the same as Run 501.

TABLE 7 Mass Ni Volume Run com- EADC Productivity MI HLMI Density No.plex (g) (mL) (g PE/g Ni) (g/10 min) (g/10 min) (g/cc) 701 0.0390 132026 0 0.05 <0.880   702 0.0393 5 43223 0 0.02 0.904

Example 8

The following experiments show the effect of added aluminophosphate tothe reaction system with two different amounts of 25% weight/weighttriisopropylaluminum (TIBA) as the alkylating agent. All experimentswere performed at 60° C. in isobutane. No polymer is formed at eitherlevel of TIBA in the absence of the aluminophosphate.

TABLE 8 Produc- Mass Ni Mass Volume tivity Run com- AlPO₄ TIBA (g PE/gNo. plex (g) (g) (mL) Ni) MI HLMI Density 801 0.0336 0.46 1 49447 00.01  802 0.0336 0.46 1 49452 0 0.01  0.8959 803 0.0373 0   1   0 8040.0410 0.43 5 30489 0 0.009 0.8985 805 0.0336 0   5   0

While this invention has been described in detail for the purpose ofillustration, it is not to be construed as limited thereby but isintended to cover all changes and modifications within the spirit andscope thereof.

That which is claimed is:
 1. A process for producing polyolefinscomprising contacting at least one olefin in a polymerization zone underpolymerization conditions with a catalyst composition produced bycombining at least one diimine complex, an aluminophosphate, and atleast one cocatalyst selected from the group consisting of alkylaluminum compounds and alkyl zinc compounds, wherein the diiminecomplex, aluminophosphate, and cocatalyst are present in such amountsthat the catalyst composition is more active than a catalyst compositionhaving the same amounts of the diimine complex and the cocatalyst but noaluminophosphate, and wherein each diimine complex is selected from thegroup consisting of nickel and palladium diimine complexes having

functionality, wherein M is Ni or Pd and each R can be the same ordifferent and is selected from the group consisting of hydrogen andbranched or linear alkyl groups or aromatic groups, said alkyl andaromatic groups having 1 to 10 carbon atoms.
 2. A process according toclaim 1 wherein each diimine complex is selected from nickel diiminecomplexes.
 3. A process according to claim 2 wherein each saidcocatalyst is selected from alkyl aluminum halide compounds, trialkylaluminum halide compounds and dialkyl zinc compounds.
 4. A processaccording to claim 3 wherein each diimine complex is selected from thegroup consisting of N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediiminenickel(II) bis(acetylacetonate);N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediimine nickel(II)(1,1,1,5,5,5-hexafluoroacetylacetonate)chloride;N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediiminebis(allylacetylacetonato) nickel(II);N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediimine nickel(II)bis(benzoylacetonate); N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediiminenickel(II) bis(benzoyl-1,1,1-trifluoroacetonate);N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediimine nickel(II)bis(1,1,1-trifluoroacetylacetonate);N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediimine nickel(II)bis(1-chloro-1,1-difluoroacetylacetonate);N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediiminebis(methyltrifluoroacetoacetonato) nickel(II);N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediimine nickel(II)bis(1,1,1-trifluoro-5,5-dimethylacetylacetonate);N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediimine bis(ethylα-methyl-4,4,4-trifluoroacetoacetato) nickel(II);N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediimine nickel(II)bis(4,4,4-trifluoro-1-(2-furyl)acetylacetonate);N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediimine nickel(II)bis(2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedionate);N,N′-bis(2,6-diisopropylphenyl)acenaphthyl nickel(II)bis(hexafluoroacetylacetonate);N,N′-bis(2,6-dimethylphenyl)-1,2-ethylenediimine nickel(II)bis(acetylacetonate);N,N′-bis(2,6-diisopropylphenyl)-1,2-ethylenediimine nickel(II)bis(hexafluoroacetylacetonate);N,N′-bis(2,6-dimethylphenyl)-1,2-ethylenediimine nickel(II)bis(hexafluoroacetylacetonate); andN,N′-bis(2,6-dimethylphenyl)-2,3-butanediimine nickel(II)bis(acetylacetonate).
 5. A process according to claim 3 whereinN,N′-bis(2,6-diisopropylphenyl)-2,3-butanediimine nickel(II)bis(1,1,1,5,5,5-hexafluoroacetylacetonate) is used in preparing thecatalyst composition.
 6. A process according to claim 5 wherein only onediimine complex is used in making the catalyst composition.
 7. A processaccording to claim 6 carried out under slurry polymerization conditions.8. A process according to claim 7 wherein the cocatalyst is selectedfrom trialkyl aluminum compounds and dialkyl zinc compounds.
 9. Aprocess according to claim 1 wherein each diimine complex is selectedfrom the group consisting of diimine nickel complexes and diiminepalladium complexes comprising additional ligands selected from thegroup consisting of α-deprotonated-β-diketones,α-deprotonated-β-ketoesters, halogens and mixtures thereof.
 10. Aprocess according to claim 2 wherein said cocatalyst is selected fromthe group consisting of non-halogenated alkyl metal compounds.
 11. Aprocess according to claim 2 wherein said cocatalyst is selected fromthe group consisting of trialkyl aluminum compounds and dialkyl zinccompounds.
 12. A process according to claim 2 wherein said process is aslurry polymerization process.